That is super progress!
FWIW, I do not have a gasket between the pump and the block. There wasn't one on the motor when I took the pump off, and I didn't put one on when I put the pump back on. I couldn't find any reference to one anywhere. I found a couple posts on various Mustang forums that all seemed to agree that if there ever was a gasket specified there, it's been discontinued a long time and isn't necessary. With that information I put the engine in the car and didn't worry.
I did pull the pan & pump on my '62 motor and it doesn't have a gasket either. I don't have an oil pressure gauge in my car (just the idiot light), but when I first started the car with the new motor the filter filled instantly and there was no clatter or noise. I don't think a gasket for the pump is a bad idea, but I also don't think it's necessary. There is a large flange there at that mating surface and the surface is well-machined. It should seal just fine. *Should*.